INSTABILITY OP LIVING MATTER 233 



function and further activity. Other poisons and physical agents 

 may likewise cause death by the contrary process of decom- 

 posing and breaking down the molecules, whereby they become 

 so gravely disorganized as to be unable to continue the pro- 

 gressive series of attachments and of liberation of side-chains 

 which are the underlying features of the vital process. 



I could expand this conception and dilate for long upon its 

 many bearings. Once we accept this chemical theory of growth, 

 if I may so term it, it is wonderful how it illuminates and 

 harmonizes a whole host of phenomena regarding which there are 

 hosts of theories, having this in common, that they do not 

 adequately explain. I could spend some hours of your time 

 applying this conception to the subjects of evolution, of descent, 

 and of inheritance, the inheritance or non-inheritance of acquired 

 properties, the inheritance of disease, the immunity from disease, 

 and so on. But I will desist ; it may seem to you that I have 

 already gone too far. But in defence of myself, I am prompted 

 to quote some words of the good old Stephen Hales, Vicar of 

 Teddington, near London, in the reign of George I., who was the 

 founder of modern exact physiology, based upon accurate 

 measurements, and quantitative rather than qualitative studies. 

 " In natural philosophy," he says, " we cannot depend on any 

 mere speculations of the mind ; we can only, with the mathe- 

 maticians, reason with any tolerable certainty from proper data 

 such as arise from the united testimony of many good and 

 credible experiments. 



" But it seems not unreasonable, on the other hand, though 

 not far to indulge, yet to carry our reasoning a little further than 

 the plain evidence of experiments will warrant ; since at the 

 utmost boundaries of those things which we clearly know, there 

 is a kind of twilight cast from what we know on the adjoining 

 borders of terra incognita. It seems therefore reasonable to 

 indulge conjecture there ; otherwise we should make very slow 

 advance in future discoveries, either by experiments or reasoning." 



I have, it may be, conducted you to this twilight land on the 

 borders of terra incognita. I shall be satisfied if I have set you 

 thinking ; if I have indicated to you, though vaguely, that life 

 is not a thing peculiar and apart : that it is a portion of a larger 

 whole ; that animate and inanimate nature conform to the same 

 laws, the same principles of chemical association and dissociation. 



